1. Field of the Invention
The present invention relates to a cross country ski having a longitudinal rib projecting upwardly with respect to its upper surface.
2. Description of Background In Relevant Information
Cross country skis are known which comprise a longitudinal rib along their upper surface. This longitudinal rib generally has a vertical trapezoidal cross section, i.e., it is defined by an upper horizontal surface and two lateral inclined surfaces. The rib, having a vertical trapezoidal cross section, is connected to the lower portion of the ski which has a right rectangular cross section, of short height, whose short sides constitute the edges of the ski. By virtue of the reduced height of the edges, such a cross country ski slides more easily on the snow. Furthermore the upper longitudinal rib contributes to the lateral guidance of the boot mounted on the cross country ski, which is adapted for this purpose by virtue of the provision, in its sole, of a groove having in vertical cross section of a shape complementary to that of the ski rib.
A cross country ski of this type is constituted by a beam casing whose wall, shaped in the manner noted above, is formed of a layered or reinforced plastic material, e.g., reinforced by carbon or glass fiber, whose interior is filled with a relatively rigid but light material such as a rigid foam.
The present invention relates to improvements applied to such a cross country ski having as an aim to improve its resistance, particularly during the practice of skating "in half skating steps", without substantially increasing its weight.